1. Field of the Invention
This application relates generally to inhibiting vapor deposition on selected surfaces, such as reactor surfaces or select surfaces on a substrate.
2. Description of the Related Art
Atomic layer deposition (ALD) is a known process in the semiconductor industry for forming thin films of materials on substrates, such as silicon wafers. ALD is a type of vapor deposition wherein a film is built up through self-saturating surface reactions performed in cycles. In an ALD process, gaseous precursors are supplied, alternatingly and repeatedly, to the substrate to form a thin film of material on the substrate. One reactant adsorbs in a self-limiting process on the wafer. A subsequent reactant pulse reacts with the adsorbed material to form a molecular layer of the desired material. The subsequent pulse can reduce or getter ligands from the adsorbed layer, can replace such ligands or otherwise add atoms (e.g., oxidize, nitridize, etc.). In a typical ALD reaction, no more than a molecular monolayer forms per cycle. Cycles can be more complex and involve three or more reactants in sequence. Some recognized advantages of ALD are low temperature processing and near perfect conformality, leading to great interest in ALD for semiconductor processing.
Other processes besides ALD exist for forming thin films of materials on substrates. One such process is chemical vapor deposition (CVD), in which a substrate is exposed to one or more volatile precursors which react and/or decompose on the substrate to form a thin film. Both ALD and CVD can be sensitive to the exposed surface; depending upon the precursors and deposition conditions, vapor deposition processes can nucleate well or poorly on different surfaces.
Invariably, during processing, deposition occurs on exposed surfaces other than those for which deposition may be desired. For example, a film buildup can occur on exposed surfaces of a reactor as multiple substrates are processed in sequence. The film buildup can delaminate or flake from the reactor surfaces and contaminate the substrate surface. Large amounts of loosely adhered film buildup on the reactor surfaces also increases the total surface area exposed to a reactant pulse, thereby increasing the pulse and purge time required to saturate substrate surfaces. In addition, films can be deposited on undesirable areas of semiconductor device structures, such as dielectric surfaces, entailing additional patterning and etch steps.
Currently, selective processes are available that prevent or reduce the amount of unwanted film deposition on reactor surfaces and device structures. One such process utilizes a treatment process that results in a protective self-assembled monolayer (SAM) over reactor surfaces and is described in U.S. Patent Application No. 2007/0098894, filed on Nov. 30, 2006. Another such process utilizes a treatment process that results in a selective deposition on substrate surfaces and is described in U.S. Pat. No. 6,391,785, filed on Aug. 23, 2000.
Improved processes for preventing or minimizing film buildup caused by deposition processes on reactor surfaces and select surfaces of device structures are thus desired.